Chapter 33

Chapter 33 - Figure 32.11 Chapter 33 Invertebrates Know the...

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Figure 32.11 Chapter 33: Invertebrates Know the definitions from Chapter 32; objective on moodle Most recent hypothesis about animal phylogeny Figure 32.11 Concept 33.1: Sponges are basal animals that lack true tissues o Live in both fresh water and marine waters o Lack true tissues and organs o Assymetrical body Sponges Sponges are suspension feeders o Filter water passing through their bodies o Figure 33.4 o Pores: doughnut shaped that span the body wall o Choanocytes: line the spongocoel, movement of flagella sets up water flow
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o Choanocytes traps food and ingest it by phagocytosis; pass it along to amoebocytes Concept 33.2: Cnidarians are an ancient phylum of eumetazoans Cnidarians A wide range of sessile and floating forms including jellyfish, corals, and hydras Simple diploblastic, radial body plan o Body plan is a sac with a central gastrovascular cavity o Single opening serves as both mouth and anus o Mesoglea layer between epidermis and endodermis (gastrodermis) Body plans o Polyp form is generally sessile o Medusa form moves freely in water by passive driving contractions of the bell o Figure 33.5 Defining Feature o Cnidocytes Unique cells that function in defense and the capture of prey o Stimulus causes the cell to evert releasing thread o Some cnidocytes sting, others just entangle prey Diversity (Table 33.1)
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How many planes through the central axis will divid an organism with radial symmetry into roughly equal halves? Many Concept 33.3: Lophotrochozoans, clade identified by molecular data, have the widest range of animal body forms Bilateria show cephalization and 3 tissue layers o Cephalization-head where sensory organs are concentrated o Lophotrochozoa-represent the different body types that we see in animals Flat worms Phylum Platyhelminthes (Table 33.2)
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Tripoblastic development but acoelomate (no body cavity)
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This note was uploaded on 03/18/2010 for the course BIOL 1202 taught by Professor Gregg during the Spring '08 term at LSU.

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Chapter 33 - Figure 32.11 Chapter 33 Invertebrates Know the...

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